20November 4, 2015
I received a question from a reader concerning mulching plants in the fall. If you have been a reader of this column for a few years, you know that I am an advocate of adding mulch around the plants in the fall. This is the reason why you mulch your plants in the fall. In the winter, the ground usually freezes. Nothing earth shattering with that statement. During the process of the ground freezing, plants get lifted out of the ground ever so slightly. This process of lifting the plants breaks a bit of the root system. This is no big deal because in the spring the plant repairs the roots. The problem arises when the soil freezes and then thaws. Each time the soil thaws, the plants settle back into the soil. As the ground re-freezes, more roots are damaged by the plants lifting up again in the soil. A continuing freeze and thaw cycle can do major damage to the roots of your plants. In some cases, the damage can be fatal to the plants. When you mulch around the plants in the fall, it helps to prevent the freeze / thaw cycle. Sure, the ground eventually freezes but that isn’t a bad thing if the ground stays frozen. A layer of much applied around the plant helps to allow the soil to slowly freeze and then the mulch prevents the soil from quickly thawing if we get warmer weather in the late fall or early winter.
The question from the reader is, “ When do we apply the mulch?” Lawn and garden professionals have debated this question for many years. For many years, straw or salt marsh hay was used as the mulch of choice. The hay was applied just after the ground froze for the first time in the winter. The reason for this was that by applying straw too early, it could provide a place for mice to spend the winter. The mice could then feed on the bark of the plants or in some cases the roots of the plants. The problem has always been the timing of applying hay around the plants. If you need to apply it after the ground freezes, you may have windy weather that allows the hay to blow away. You may have snow that arrives before the ground freezes making it almost impossible to properly mulch the plants. It is for these reasons that I have tried to get people to apply bark mulch around the plants in the fall. Bark mulch can be applied at any time in the fall. It only needs to be applied on top of the soil around the root zone of the plant. In the case of rose bushes where you are trying to mound the mulch up onto the canes to protect the canes, the mulch can be applied as soon as the plants go dormant. The timing on that depends on the weather. In your perennial gardens, you can apply the bark mulch as soon as you cut the plants back. Shrubs can be mulched as soon as the plants begin to go dormant. The nice thing about using bark mulch is that you don’t have to pick it up and dispose of it in the spring like you would have to do if you use hay. The other nice thing is that with bark mulch you can apply it earlier in the fall without having to wait for the ground to freeze. This can be especially important for those of you who head south for the winter.
A 3-inch layer of mulch is applied around the plant covering the soil in the area where the roots are in the soil. This cuts down on the freeze / thaw cycle. This allows the soil to slowly freeze and then prevents the soil from quickly thawing out if the weather warms up again in the winter. This can be especially helpful to plants that were planted in late summer or fall. These plants may not have had time to fully develop a root system in the soil. By mulching them in the fall, it slows down the freezing of the soil, allowing the plants more time to establish a stronger root system before the ground freezes.
If your mulch of choice is hay or straw, you will have to wait until the ground freezes before you apply a winter mulch. If you use bark mulch, you can really apply it at any time. My feeling is that by using bark mulch, you don’t necessarily have to wait for a freezing of the soil. Once the temperatures are staying cold you can mulch your plants for the winter. Come the spring, you can thin out the bark mulch and then mulch as you normally would in the spring.
Hopefully this has helped to answer the question about mulching plants before winter sets in. If not, feel free to stop by the store and any of our employees can help you to make a decision about when it is best for you to be applying a winter mulch.
Well, that’s all for this week. I’ll talk to you again next week.